The current state of the art, in the field of coil spring mattress construction, is shown in FIG. 1 and FIG. 2 of U.S. Pat. No. 7,640,611B1. FIG. 1 is a perspective and partial cut-away view of a mattress depicting various components of a mattress construction, and FIG. 2 is a cross-sectional view of the mattress of FIG. 1. FIGS. 1 and 2 are reproduced from my U.S. Pat. No. 7,640,611B1, which patent is incorporated herein in its entirety by this reference.
Referring to FIGS. 1 and 2, a generally planar base for the mattress 10 is constructed of a planar base foam layer 12 and fiberboard layer 14. Affixed along the perimeter of the base, by conventional gluing methods, are foam rails 16, rectangular in cross-section. The foam rails 16 form a rectangular all-foam encasement 18 (FIG. 1) defining a rectangular interior cavity 17 (FIG. 1), within which is placed a plurality of coil springs 19 (some of which are indicated by numeral 19 in FIG. 1), which are tied together, forming a coil spring unit 20. Each of the foam rails 16 have dimensions of approximately six inches (15.24 cm) in height and four inches (10.16 cm) in width, the lengths of the foam rails 16 being dictated by the desired size of the mattress.
A border assembly of fabric 22 including an outer layer of quilted material 23 is wrapped around the all-foam encasement 18 (FIG. 1) and attached to the outer sidewalls of the foam rails 16 by gluing and/or by means of divergent staples as described in U.S. Pat. No. 7,640,611B1.
While the all-foam encasement 18 and attached border assembly 22 are suitable for extended usage, there is a need in the ultra-premium class of mattresses for a construction which provides even more substantial border support, and which insures that the edges provided by the encasement remain straight and durable over time, in order to prevent sleeper roll off and dislodging of the border assembly, over time, due to the natural movement and weight of the sleeper on the mattress.